Stoker



July 11, 1939. c. H. SNYDE-R El AL STOKER Filed May 2, 1936 H VENTORS'. WW

- flpf-ATTORNEY 5 fuel bed. Only after a lengthy firing period does provided with an interior chamber I2 opening 35 main July 11,1939 I v v 0 2,106,080

UNITED STATES PATENT OFFICE;

s'roxsa Cliilord H. Snyder, Dormont, and Andrew W. Fergnor Bellevue, Pa.; said Ferguson assignor to said Snyder Application May 2, 1936, Serial No. 77,508

Claims. (Cl. 110-45) This invention relates generally to solid fuel Another object of this invention is the proviburning, and more particularly to a method and sion of means for agitating thecoal by displacemeans for agitating said fuel as it is being burned. ment, as it is being coked, so that the coked par- This invention may be conveniently applied to ticles more readily correspond to the particles of 5 stokers arranged to burn solid fuel, and is parcoal from which they were formed. 5 ticularly adaptable to underfed stokers. Another object of this invention is the provi- In underfed stokers coal is fed from below by sion of means for agitating the coke by displacemeans of a screw or other conveying or propelling ment, thereby loosening the coked fuel to maindevice, and a forced draft is usually applied under tain a loose fire bed that may be readily penev in or into the fire to support and accelerate forced trated by a forced draft to promote better comin combustion of the fuel. These two operations bustion, thereby producing more rapid converare usually served by a motor or motors enersion of the fuel into'heat. gized by automatic electric controls. These con- Other objects and advantages will appear here-' trols operate the stoker in a cycle which may be inafter. 1 divided into two distinct periods, namely the In the accompanying drawing wherein we show firing period and the dormant period. a practical embodiment of the principles of this During the firingperiod as the fresh green invention: I coal is fed upwardly through the retort from be- Fig. 1 is a vertical section taken through the low it is preheated by the fire or hot coals therefeeding mechanism and retort of a typical auto- 90 above. With coking coals and many so-called matic stoker, showing the application of this innon-coking coals, as this preheating action takes vention, parts being broken away. place the gases and natural oils are driven ofi Fig. 2 is a vertical section of a modified form and the coal particles become soft or semi-plastic, of the power transmission for operating the agiadhering one to the other, and ultimately formtating device of this invention. ing a solid mass of coke. This solid mass is Fig. 3 is a vertical section of a retort showing 5 moved upward by the feeding of new green coal a modification of this invention applied thereto, from below and,'instead of spreading out to form with parts being broken away. an even fuel bed as is desirable, it usually con- 4 is a side elevation looking to the right tinues to build up, forming a hard shaft of coke, of the line 44 in Fig. 3. commonly known in the stoker industry as a Referring to Fig. I of the drawing, l0 repre- 30 "coke tree. s sents the retort of an automatic underfed stoker The forced draft is unable to penetrate this arranged to be inserted or built into the fire box coke tree so that blow holes usually exist around of a furnace or other related unit. This retort its base which results in a poor heat producing comprises the tuyre I l, upwardly expanding,

this coke tree build up to a height great enough at the bottom It thereof for the conduction of to fall over of its own weight, in which case the 'air and provided with a plurality of inwardly difire is sometimes lifted out of the retort, or the rected passageways l4 ending in the ports l5 coke tree comes into contact with some obstrucwhich open through the inner wall 01' the tuyere.

40 tion in its travel that will cause it to buckle and Likewise the outer adjacent side wall of the 40 fall. However due to the large quantity of untuyere is provided with the passageways It for burned fuel in the coke tree the fire often condirecting air from the chamber l2 along the floor tinues to give off an excessive amount of heat line l1. with a corresponding waste of fuel during the The tuyre II is mounted on the retort base I8 5 dormant period, long after the demand for heat which comprises an inner casing IS. The inner has been satisfied. In an effortto avoid these bore of the casing l9 forms the throat 20, the v and the other coke tree disadvantages many surface of which is continuous with the-inner stoker owners rake and poke the coke trees and surface of the tuyre ll. level the fire by hand at frequent intervals. One side of the lower end of the casing I9 is The principal object of this invention is-the provided with the passageway or conduit 2| for 50' provision of agitating means for the preventing admitting fuel to the bottom of the retort III. of the formation of solid masses of coke in the A portion of the wall opposite the mouth of the fuel before the fuel moves upwardly into the zone conduit 2! deflects the fuel verticallyupward of combustion to maintain a homogeneous fuel through the throat to the burner or fire bowl bed. formed by the tuyere ll.

The outer and lower part of the base lit forms the Wind box 22 which is connected to a source of air supply and serves to distribute the air evenly into the passageways it and it of the tuyere.

23 represents a screw for feeding solid fuel to the base of the retort, and which extends from the operating mechanism it through the base 25 of the fuel hopper 2t, and through the screw housing 27 into the passageway M in the base it of the retort ill.

When the operating mechanism 26 is started, the screw 23 is rotated, thereby receiving coal from the hopper 2t and moving it through the housing 2i into the bwe it of the retort.

As coal is being fed to the retort it moves through the throat it into the fire zone in the bowl formed by the tuyere "if and should spill,

iii)

in a semi-burned condition, over the top thereof onto the floor ll. During this time the wind box 22 is delivering air to the passageways it and it of the tuyere ll from whence it is forced into the burning fuel;

- The coal in the lower part of the tuyere bowl i9 and in the throat it is being preheated and gassed and coke is formed. As the temperature increases in the preheating area or zone, the particles of coal change to a soft state due to the reaction of the natural oils therein, the coal particles having a tendency to adhere one to another and to form a solid mass of hard texture coke, as the gases and oils are driven off and the heat dries out the thus formed colic.

One object of this invention is to prevent this coke from forming into a solid mass by providing the retort ill with the agitator bar 3t which in Fig. l, is shown to be a section of a ring, the center of which is located at the point 3i. agitator is preferably circular in cross section and is supported at the lower end by the linhili pivoted at 39 and riding in the bearing 32} of the casing it, which bearing is formed to fit the perimetral contour of the agitator bar.

36 represents a transmission rod which is connected at one end to and which is arranged to be reciprocated by the crank iii operated by the pinion 35 which in turn is driven by the beveled ring gear ill afiixed to the rotary shaft 28.

The other end of the transmission rod it is provided with a bifurcated member iltl which is pivotally secured in the bearing near the outer end of the link 32.

Thus when the fuel screw it is operated, the shaft 28 will drive the crank arm it through the gears 36 and ill, thereby reciprocating the rod t t and driving the" agitator bar up and down through the threat in and the tuyere if (as indicated by the dotted and dash lines) to meet particular requirements.

As indicated in the drawing, the gear ratio between the pinion 3B and the ring gear ill is four to one, whichcauses the agitator bar iii to reciprocate four times within the retort it to every complete revolution of the feeding screw lit. This ratio however may be changed according to varying conditions.

it represents a passageway in the center of the agitator bar which may be employed to conduct 'air from the wind box 22 to the center of the retort as the agitator bar is reciprocated therein. This air passage also aids in cooling the agitator bar 38.

The agitator bar 30 working through the retort ill during the firing period of the operating cycle, moves the coke forming therein in a rolling and is ready to start another cycle.

The

areaooc churning manner which prevents its coagulating into a unitary mass. It not only agitates the fuel by the intermingling of a moving object among the fuel particles but it does even more by the displacement which takes place. For ex ample:-Ey the insertion of this agitator bar from an external point, the coal is moved which first fills in much of the space (openings, com monly called voids) between the other particles of coal. Continuing the stroke, it rolls and churns the particles of coal being coked so that they do not adhere solidly one to another. The agitator bar should still continue its travel causing a gentle upheaving of the surface of the fuel bed, thereby keeping the fuel bed in a loose state, permitting a more uniform penetration of the ill) forced or natural draft with less resistance, and

thereby requiring a lower volume oi air for cornbustion. Much the same action takes place on the return stroke of the agitator bar. The upper surface of the iuel bed gently smooths down, the coking particles below again churn about as they fill in the space formerly occupied by the agitator bar. the meantime a small supply of new green coal has been fed in and the agitator bar Thus the fuel forms into small friable units composed of small colic particles approximating the size of the fuel being fed, but lightly adhering together. The spreading of this fuel by the agitator provides a homogeneous and very desirable type of fire bed. Thus the coke tree or conin hereinbefore mentioned, is eliminated as well as its consequent long firing periods and waste of fuel.

it will of course be understood that the screw while in operation may be continuously or inter mittently rotated. Again the agitator member may be operated from or with the screw or other feeding device, or it may be independently operated either mechanically, or if desired manually.

Referring to Fig. 2, ill represents a cylindrical earn member owned to the shaft 26 and having a cam slot d2. db represents a rod head member. secured at one end to the transmission rod 34 and passing at dd through the housing which encases the cam member. The other end of the member 413 is provided with the follower (iii ar-' ranged to ride in and be guided by the cam slot 432 of the cam member ii. A hardened steel pin may be employed for this purpose. However it may be preferable to provide a stub shaft with a roller or other antifriction bearing arranged to ride in the cam slot df.

Referring now to Figs. 3 and 4, it represents a vertically disposed agitating member arranged to reciprocate within the retort it. The upper end of the member may be provided with fingers or projections similar to that shown at ll for further agitating the fuel. The agitating member may be made up of the upper and lower parts it and 49 which are rotatably secured to one another by means of the bolt Fit and spaced apart by a thrust bearing ill. The upper part it is provided with the spiral groove iii formed longitudinally thereof and arranged to receive theiinner end of the pin lit secured in the casing 5 which in turn is secured to the base it) of the retort. Thus as the agitating member 88 is reciprocated vertically,

the upper part tit, is rotated by the action oi the spiral groove with the pin 53.

of the crank pin Bl extending laterally from the lower end of the crank arm 59. The other end of the crank arm 59 is secured to the'shaft 60 Jour-' naled in the frame GI.

62 represents a transmission shaft journaled in the upper part of the frame SI and-extendingto the operating mechanism, from whence it derives its rotary motion. The shafts 60 and B2 are provided with the meshed gears 63 and 64 respectively. These gears may be changed to vary the ratio of the reciprocal movement of the agitator 46 with respect to the fuel feeding screw, but they are shown herein as one to one ratio gears.

The operation of this agitator is similar to that shown in Fig. 1 and produces the same effects.

In all these embodiments the agitators of this invention are arranged to reciprocate into the retort from or at the under side of the bodyof fire to churn the coking coals and displace them v upwardly. If the coals have any tendency to coagulate, the force of the agitators is first directed 'on the particles of green coal and upwardly to and through the coking particles of the fuel, displacing considerable coal.

- Our agitator may be arranged either to be r wholly withdrawn from the combustion chamber automatic stokers.

We claim:

1. In an underfed stoker of the character described, the combination of a vertically disposed retort having an upwardly extending wall forming an enclosed throat in the upper portion of which combustion of the fuel occurs, a horizontal conduit communicating with the lower end of the throat at one side thereof, means for introducing iuel through the conduit into the bottom of the P throat, the portion of the wall opposite the mouth of the conduit deflecting the fuel vertically upward through the throat, an agitator member having its free end extending into the throat through an opening in the bottom thereof, and

means for moving said membersubstantially ver tical into and out of the fuel in the throat below the zone of.combustion to prevent the formation of solid masses of coke.

2. In an underfed stoker of the character described, the combination of a vertically disposed retort having an upwardly extending wall forming an enclosed throat'in the upper portion of which combustion of the fuel occurs, a horizontal conduit communicating with the lower end of the throat at one side thereof, means for introducing fuel through the conduit into the'bottom of the throat, the portion of the wall opposite the mouth of the conduit deflecting the fuel vertically upward through the throat, an agitator member having its free end extending into the throat through an opening in the lower portion thereof below the plane of the uppermost. portion of said conduit, and means for moving said agitator member into and out of the fuel in the throat transversely to the path of the fuel entering the throat and below the zone of combustion to prevent the formation of solid masses of wire.

3. In an underfed stoker of the character described, the combination of a vertically disposed retort having an upwardly extending wall forming an enclosed throat in the upper portion'of which combustion of the fuel occurs, a horizontal conduit communicating with the lower end of the throat at one side thereof, means for introducing fuel through the conduit into the bottom of the throat, the portion of the wall opposite the mouth of the conduit deflecting the fuel vertically upward through the throat, an agitator member having its free end extending into the throat through an opening in said deflecting wall and having its longitudinal axis disposed transversely to the path. of the fuel entering the throat, and means for moving said agitator member into and out of the .fuel in the throat below the zone of combustion to prevent the formation of solid masses of coke.

4. In an underfed stoker of the character described, the combination of a vertically disposed retort having an upwardlyextending wall forming' an enclosed throat in the upper portion of which combustion of the fuel occurs, a horizontal conduit communicating with the lower end of the throat at one side thereof, means for introducing fuel through the conduit into the bottom of the throat, the portion of the wall opposite the mouth of the conduit deflecting the fuel vertically upward through the throat, a longitudinal arcuate agitator bar having its free end extending through an opening in the lower portion of the throat below the plane of the uppermost portion of said conduit, said bar being ivotally supported on an axis located at a point e teriorto and above the bottom of the throat, and means for swinging said member on said axis into and out of the fuel in the throat below the zone of combustion to prevent the formation of solid masses of coke.

5. In an underfed stoker of the character described, the combination of a base arranged to be inserted in the bottom of a furnace, a vertically disposed retort supported by the base and having an upwardly extending wall forming an enclosed throat in the upper portion of which combustion of the fuel occurs, a horizontal conduit connected with the lower end of the throat at one side thereof, means for introducing fuel through the conduit into the bottom of the throat, the portion of the wall opposite the mouth of the conduit deflecting the fuel vertically upward through the throat, an arm pivotally secured to the base and arranged to swing in an arc, an agitator member attached at one end to the arm and having its.

free end extending through an opening in the lower portionof the throat below the plane of the uppermost portion of said conduit with its longitudinal axis disposed transversely to the path of the fuel entering the throat. and means for swinging said member to move'its free end into nectedwith lower end of the throat at one side thereof, means for introducing fuel through the conduit into the bottom of the throat, the portion of the wall opposite the mouth of the conduit deflecting the fuel vertically upward through the throat, an arm pivotally secured to the base and arranged to swing in an are, an agitator member attached at one end to the arm and having its free end extending through an opening in the lower portion of the throat below the plane of the scribed, the combination of a vertically disposed retort having an upwardly extending wall forming an enclosed throat in the upper portion of which combustion of the fuel occurs, a horizontal conduit communicating with the lower end of the throat at one side thereof, means for introducing fuel through the conduit into the bottom of the throat, the portion of the wall opposite the mouth of the conduit deflecting the fuel vertically upward through the throat, an agitator member having its free end extending into the throat through an opening in the lower portion thereof below the plane of the uppermost portion of said conduit, a rotary crank arm connected to said member, and means for rotating said crank arm to move the agitator i'nember into and out ofthe fuel in the throat in a path transversely disposed to the fuel entering the throat and below the zone of combustion to prevent the formation of solid masses of coke.

8. In an underfed stoker of the character described, the combination of a vertically disposed retort having an upwardly extending wall forming an enclosed throat in the upper portion of which combustion of the fuel occurs, a horizontal conduit communicating with the lower end of the throat at one side thereof, a rotary screw in said conduit for introducing fuel into the bottom of the threat, the portion of the wall opposite the mouth of the conduit deflecting the fuel vertically upward through the throat, an agitator member having its free end extending into the throat through an opening in the lower portion thereof below the plane of the uppermost portion of said conduit, a drive shaft for rotating the screw, and means operated by said drive shaft for moving said agitator member into and out of the fuel in the throat in a path transversely disposed to the fuel entering the throat and below areaceo the zone of combustion to prevent the formation of solid masses of coke, said means operating the agitator member at a greater frequency than the rotation of the screw.

9. In an underfed stoker of the characterdescribed, the combination of a vertically disposed retort having an upwardly extending wall forming an enclosed throat in the upper portion of which combustion of the fuel occurs, a horizontal conduit communicating with the lower end of the throat at one side thereof, means for introducing fuel through the conduit into the bottom of the throat, the portion of the wall opposite the mouth of the conduit deflecting the fuel vertically upward through the throat, an agitator member having its free end extending into the throat through an. opening in the lower portion thereof below the plane of the uppermost portion of said conduit, means defining a passageway through the body of said agitator for directing air into the fuel in the throat, and means for moving said agientering the throat and below the zone of combustion to prevent the formation of solid masses of coke.

10. In an underfed stoker of the character described, the combination of a vertically disposed retort having an upwardly extending wall forming an. enclosed throat in the upper portion of which combustion of the fuel occurs, a horizontal conduit communicating with the lower end of the throat at one side thereof, means for introducing fuel through the conduit into the bottom of the throat, the portion of the wall opposite the mouth 'of the conduit deflecting the fuel vertically upward through the throat, an agitator member having its free end extending into the throat through an opening in the lower portion thereof below the plane of the uppermost portion of said conduit, means for moving said agitator member into and out of the fuel in the throat below the zone of combustion in a path transversely disposed to the fuel entering the throat, and means for imparting rotary movement to said agitator member to prevent the formation of solid masses of coke.

CLIFFORD H. SNYDER. ANDREW W. FERGUSON. 

